Low viscosity lubricating oils with improved oxidative stability and traction performance

ABSTRACT

Provided is lubricating oil composition including from 10 to 90 wt % of a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) produced by oligomerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, in the presence of a Lewis acid catalyst, and the remainder of the composition including one or more lubricating oil additives. The lubricating oil composition provides an oxidative stability of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/737,197, filed on 27 Sep. 2018, the entire contents of which are incorporated herein by reference.

FIELD

This disclosure relates to ultra-low viscosity and low volatility lubricating oil compositions having outstanding oxidative stability and traction performance. More particularly, the ultra-low viscosity and low volatility lubricating oil compositions incorporate a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”). The lubricating oil compositions are particularly useful for formulating 0W grades engine oils.

BACKGROUND

Modern regulations are forcing auto builders to address new daunting CO₂ emission and fuel economy (FE) requirements which are escalating rapidly on a global scale. To meet these requirements, new engine and lubrication technologies are needed. Among the array of new technologies that are being progressed is the use of ultra-low viscosity lubricants to gain energy efficiency in engine applications. The development of ultra-low viscosity synthetic base stocks having controlled volatility would enable finished ultra-low viscosity lubricants to achieve step-out FE performance. Low viscosity synthetic base stocks (kinematic viscosity of 2-3 cSt at 100° C.) are currently commercially available (for example 2 cSt PAO). However these low viscosity synthetic base stocks are too volatile to be used for formulating next-generation ultra-low viscosity engine oils (i.e., SAE “0W-4”, SAE 0W-8, SAE 0W-12, etc.).

Automotive engine oils typically conform to the SAE J300 metric for grading engine oil viscosity. For each SAE engine oil grade (e.g., 0W-4, 0W-8, 0W-12, 5W-10, 5W-20, 10W-30, etc.) there are maximum and minimum viscosity requirements at both high and low temperatures. Typically, such high temperature viscosity requirements are expressed as a permitted range of kinematic viscosity at 100° C. determined pursuant to ASTM D445 (“KV100”), and such low temperature viscosity requirements are expressed as a permitted range of cold cranking simulator viscosity determined pursuant to ASTM D5293 (“CCSV”). For example, the requirements for a 0W grade engine oil include a KV100 of at least 3.8 cSt, and a CCSV at −35° C. no higher than 6,200 mPa·s.

Recently, API Group IV base stocks, which are polyalpha-olefins (“PAO”), have found wide use in high-quality engine oils in various grades, gear box lubricants, and industrial oils. Currently low-viscosity Group IV PAO base stocks having a KV100 in the range from 3 to 10 cSt made from oligomerization of alpha-olefin monomer(s) comprising 8-12 carbon atoms in the presence of a Lewis acid catalyst such as BF₃ (“conventional low-viscosity PAO”) are commercially available. These conventional low-viscosity PAO base stocks are substantially free of dimers of the monomer(s), and tend to comprise trimers and/or higher oligomers of the alpha-olefin monomer(s) at various concentrations. The trimer and higher oligomer molecules in these base stocks tend to be highly branched (containing more than 2 branches per oligomer molecule on average). While these base stocks provide good performances, to formulate high-quality engine oils for the newer generation engines of modern automobiles, base stocks with even lower viscosity, higher viscosity index, low Noack volatility, and high blending performances in terms of blended to CCSV are needed.

Lubricant oxidative stability is one of the key parameters controlling oil life, which translates in oil drain interval in practical terms. Additionally, deposit formation is an issue associated with the decomposition of the base stock molecules mostly propagated by oxidative chain reactions. There are several conventional approaches to improve the resistance to oxidation of a finished lubricant product, but most products are formulated using small molecules such as diphenylamine (DPA) or a phenolic antioxidant. Improved oxidation stability is necessary to increase oil life and oil drain intervals, thus reducing the amount of used oil generated as a consequence of more frequent oil changes. Longer oil life and oil drain intervals are key benefits that are desirable to end customers. Traditional antioxidant packages provide standard protection leaving the main differentiation hinging on the quality of the base stock in the formulation.

Currently available commercial low-viscosity PAO base stocks do not adequately allow formulation of ultra-low viscosity lubricants while still meeting API specification (e.g., Noack volatility of 15% or less). New low viscosity engine oils, which meet the API Noack volatility limit are needed to allow for improvements in fuel efficiency while maintaining acceptable oxidative stability. In particular, there is a need for an ultra-low viscosity engine oil incorporating a low viscosity synthetic base stock having controlled volatility that would enable the finished ultra-low viscosity lubricant to achieve step-out FE performance while also providing for low friction (traction) and oxidation performance benefits relative to currently commercially available engine oils incorporating low viscosity Group IV PAO.

SUMMARY

It has been surprisingly and unexpectedly discovered that lubricating oil compositions including a major amount of a low viscosity synthetic base stock comprising oligomers of linear mono-olefin(s) having 14 or 16 carbon atoms or mixtures thereof made by using conventional Lewis acid catalyst comprising dimers and optionally trimers with a minor amount of one or more lubricating oil additives provide a lubricating oil composition with a high-viscosity-index, a low pour point with excellent oxidative stability and traction performance. These lubricating oil compositions are suitable for high-quality engine oils that provide for improved fuel economy.

A first aspect of this disclosure relates to a lubricating oil composition comprising from 10 to 90 wt % of a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) produced by oligomerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, in the presence of a Lewis acid catalyst, and the remainder of the composition comprising one or more lubricating oil additives. The lubricating oil composition provides an oxidation stability test performance of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.

Another aspect of this disclosure relates to a lubricating oil composition comprising: from 10 to 90 wt % of a base stock comprising a C28 to C32 hydrocarbon first fraction at a concentration in the range from 80 to 100 wt %, and a C42 to C48 second fraction at a concentration in the range from 0 to 20 wt %, based on the total weight of the base stock; wherein the base stock has a kinematic viscosity at 100° C. as determined pursuant to ASTM D445 (“KV100”) in the range from 3.3 to 4.6 cSt; a pour point as determined pursuant to ASTM D5850 in the range from −45 to −10° C.; and a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. of at least 500 mPa·s; and the remainder of the composition comprise one or more lubricating oil additives. The lubricating oil composition provides an oxidative stability test performance of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.

Further objects, features and advantages of this disclosure will be understood by reference to the following drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a table showing the physical properties of the inventive and comparative commercial base stocks of this disclosure.

FIG. 2 is a table showing inventive and comparative engine oil formulations and their physical characteristics and performance test results of this disclosure.

FIG. 3 is a table showing inventive and comparative SAE grade engine oils formulations and their physical characteristics of this disclosure.

DETAILED DESCRIPTION Definitions

“About” or “approximately”—All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

“Major amount” as it relates to components included within the lubricating oils of the specification and the claims means greater than or equal to 50 wt. %, or greater than or equal to 60 wt. %, or greater than or equal to 70 wt. %, or greater than or equal to 80 wt. %, or greater than or equal to 90 wt. % based on the total weight of the lubricating oil.

“Minor amount” as it relates to components included within the lubricating oils of the to specification and the claims means less than 50 wt. %, or less than or equal to 40 wt. %, or less than or equal to 30 wt. %, or less than or equal to 20 wt. %, or less than or equal to 10 wt. %, or less than or equal to 5 wt. %, or less than or equal to 2 wt. %, or less than or equal to 1 wt. %, based on the total weight of the lubricating oil.

“Essentially free” as it relates to components included within the lubricating oils of the specification and the claims means that the particular component is at 0 weight % within the lubricating oil, or alternatively is at impurity type levels within the lubricating oil (less than 100 ppm, or less than 20 ppm, or less than 10 ppm, or less than 1 ppm).

“Other lubricating oil additives” as used in the specification and the claims means other lubricating oil additives that are not specifically recited in the particular section of the specification or the claims. For example, other lubricating oil additives may include, but are not limited to, antioxidants, detergents, dispersants, antiwear additives, corrosion inhibitors, viscosity modifiers, metal passivators, pour point depressants, seal compatibility agents, antifoam agents, extreme pressure agents, friction modifiers and combinations thereof.

“Alkyl group” refers to a saturated hydrocarbyl group consisting of carbon and hydrogen atoms.

“Hydrocarbyl group” refers to a group consisting of hydrogen and carbon atoms only. A hydrocarbyl group can be saturated or unsaturated, linear or branched, cyclic or acyclic, and aromatic or non-aromatic.

“Hydrocarbon” refers to a compound consisting of carbon atoms and hydrogen atoms.

“Alkane” refers to a hydrocarbon that is completely saturated. An alkane can be linear, branched, cyclic, or substituted cyclic.

“Olefin” refers to a non-aromatic hydrocarbon comprising one or more carbon-carbon double bond in the molecular structure thereof.

“Mono-olefin” refers to an olefin comprising a single carbon-carbon double bond.

“Cn” group or compound refers to a group or a compound comprising carbon atoms at total number thereof of n. Thus, “Cm-Cn” group or compound refers to a group or compound comprising carbon atoms at a total number thereof in the range from m to n. Thus, a C1-C50 alkyl group refers to an alkyl group comprising carbon atoms at a total number thereof in the range from 1 to 50.

“Carbon backbone” refers to the longest straight carbon chain in the molecule of the compound or the group in question. “Branch” refer to any substituted or unsubstituted hydrocarbyl group connected to the carbon backbone. A carbon atom on the carbon backbone connected to a branch is called a “branched carbon.”

“Epsilon-carbon” in a branched alkane refers to a carbon atom in its carbon backbone that is (i) connected to two hydrogen atoms and two carbon atoms and (ii) connected to a branched carbon via at least four (4) methylene (CH₂) groups. Quantity of epsilon carbon atoms in terms of mole percentage thereof in a alkane material based on the total moles of carbon atoms can be determined by using, e.g., ¹³C NMR.

“SAE” refers to SAE International, formerly known as Society of Automotive Engineers, which is a professional organization that sets standards for internal combustion engine lubricating oils.

“SAE J300” refers to the viscosity grade classification system of engine lubricating oils established by SAE, which defines the limits of the classifications in rheological terms only.

“Base stock” or “base oil” interchangeably refers to an oil that can be used as a component of lubricating oils, heat transfer oils, hydraulic oils, grease products, and the like.

“Lubricating oil” or “lubricant” interchangeably refers to a substance that can be introduced between two or more surfaces to reduce the level of friction between two adjacent surfaces moving relative to each other. A lubricant base stock is a material, typically a fluid at various levels of viscosity at the operating temperature of the lubricant, used to formulate a lubricant by admixing with other components. Non-limiting examples of base stocks suitable in lubricants include API Group I, Group II, Group III, Group IV, and Group V base stocks. PAOs, particularly hydrogenated PAOs, have recently found wide use in lubricants as a Group IV base stock, and are particularly preferred. If one base stock is designated as a primary base stock in the lubricant, additional base stocks may be called a co-base stock.

“In the vicinity of” a given temperature means within the range from 10° C. lower than that temperature to 10° C. higher than that temperature.

“Substantially saturated” means at least 90%, preferably at least 95%, more preferably at least 98%, by mole, of the molecules in question are saturated, based on the total moles of the relevant molecules.

“Substantially free” of the monomer(s) means a material comprises the monomer(s) at a total concentration thereof, of no more than 5%, preferably no more than 3%, more preferably no more than 1%, by weight, based on the total weight of the material.

All kinematic viscosity values in this disclosure are as determined pursuant to ASTM D445. Kinematic viscosity at 100° C. is reported herein as KV100, kinematic viscosity at 40° C. is reported herein as KV40 and kinematic viscosity at 25° C. is reported herein as KV25. Units of all KV100, KV40 and KV25 values herein are cSt unless otherwise specified.

All viscosity index (“VI”) values in this disclosure are as determined pursuant to ASTM D2270.

All Noack volatility (“NV”) values in this disclosure are as determined pursuant to ASTM D5800 unless specified otherwise. Unit of all NV values is wt %, unless otherwise specified.

All pour point values in this disclosure are as determined pursuant to ASTM D5950 or D97.

All CCS viscosity (“CCSV”) values in this disclosure are as determined pursuant to ASTM 5293. Unit of all CCSV values herein is millipascal second (mPa·s, which is equivalent to centipoise), unless specified otherwise. All CCSV values are measured at a temperature of interest to the lubricating oil formulation or oil composition in question. Thus, for the purpose of designing and fabricating engine oil formulations, the temperature of interest is the temperature at which the SAE J300 imposes a minimal CCSV.

All percentages in describing chemical compositions herein are by weight unless specified otherwise. “Wt. %” means percent by weight.

Lubricating Oil Compositions Containing Dimer Base Stock of this Disclosure

In this disclosure, a “lubricating oil composition or formulation” refers to lubricating oil product that can be directly used to lubricate the interface between two surfaces moving relative to each other without the need to add any additional material. A lubricating oil composition in this disclosure can be, among others: (i) a pure base stock and one or more lubricating oil additives, and (ii) a mixture of a base stocks (for example, a first base stock and a second base stock or cobase stock) and one or more lubricating oil additives. Therefore, to make a final lubricating oil composition or formulation of a product, one may add additional components, such as other base stocks, additional quantities of the materials already present in the oil composition, additive components, and the like.

While it is possible the oil composition of this disclosure contains the base stock as a primary base stock, or even as a single base stock, it is preferable to include the base stock as a co-base stock in combination with one primary base stock and optionally one or more additional co-base stocks. In addition to the base stocks, the oil composition of this disclosure may further comprise additive components.

More particularly, this disclosure relates to lubricating oil compositions including a low viscosity low volatility base stock (for example 3.5 cSt) including a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) made by using a conventional Friedel-Crafts BF3 catalyst and higher molecular weight alpha olefin (1-tetradecene) to and one or more lubricating oil additives that provides for improved oxidative stability and friction (traction) performance. The low viscosity base stock including a C14 dimer (C28 Group IV base stock) has a novel structure, as demonstrated by 1H and 13C NMR methyl hydrogen and epsilon carbon contents and ratio, which provides for the improvement in physical properties and performance characteristics when incorporated into a lubricating oil composition. The lubricating oil compositions including the C14 dimer have low Noack volatility and improved fuel economy when used as engine oils relative to comparable lubricating oil compositions including low viscosity PAO as the base stock.

In one advantageous form of the lubricating oil composition of this disclosure includes from 10 to 90 wt % of a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) produced by oligomerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, in the presence of a Lewis acid catalyst, and the remainder of the composition comprising one or more lubricating oil additives. The lubricating oil composition provides an oxidative stability test performance of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.

In another advantageous form of the lubricating oil composition of this disclosure includes from 10 to 90 wt % of a base stock comprising a C28 to C32 hydrocarbon first fraction at a concentration in the range from 80 to 100 wt %, and a C42 to C48 second fraction at a concentration in the range from 0 to 20 wt %, based on the total weight of the base stock; wherein the base stock has a kinematic viscosity at 100° C. as determined pursuant to ASTM D445 (“KV100”) in the range from 3.3 to 4.6 cSt; a pour point as determined pursuant to ASTM D5850 in the range from −45 to −10° C.; and a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. of at least 500 mPa·s; and the remainder of the composition comprise one or more lubricating oil additives. The lubricating oil composition provides an oxidative stability test performance of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 140 deg. C. of less than 0.0081.

Preferred lubricating oil compositions of this disclosure exhibit an oxidative stability test performance (time to 200% KV@40 deg. C. increase) of greater than 100 hours, or greater than 110 hours, or greater than 120 hours, or greater than 130 hours.

Preferred lubricating oil compositions of this disclosure exhibit a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081, or less than 0.0079, or less than 0.0077, or less than 0.0075, or less than 0.0073, or less than 0.0071.

Preferred lubricating oil compositions of this disclosure exhibit a kinematic viscosity at 25° C. (KV25) that is at least 0.5%, or at least 1.0%, or at least 5%, or at least 7%, or at least 10%, or at least 12% lower or less relative to a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”). In addition, the preferred lubricating oil compositions of this disclosure exhibit a cold-crank-simulator viscosity (“CCSV”) at −35° C. that is at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30% lower or less relative to a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).

Preferred lubricating oil compositions of this disclosure exhibit a KV100 in a range from kv1 to kv2, where kv1 and kv2 can be 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, as long as kv1<kv2.

Engine oil lubricant grades are determined pursuant to SAE J300 specifications. The low temperature (W) grades (i.e. 10W-xx, 5W-xx, and 0W-xx) are determined by the performance in a combination of viscosity tests including cold crank simulation (CCS) (ASTM D5293) and low-temperature pumping viscosity (ASTM D4684). The high temperature grading for an engine oil (i.e., XW-20, XW-30) is determined by kinematic viscosity at 100° C. (ASTM D445) and high-temp high-shear viscosity (ASTM D4683).

The lubricating oil compositions of this disclosure may advantageously exhibit a VI in the range from about 30 to about 200, preferably from about 35 to about 180, more preferably from about 40 to about 150.

The lubricating oil compositions of this disclosure advantageously exhibit a Noack Volatility (NV) value of no greater than 20%, preferably no greater than 18%, 16%, 15%, 14%, 12%, 10%, or even 8%.

The lubricating oil compositions of this disclosure are particularly advantageous as engine oil for internal combustion engines, including gas engines, diesel engines, natural gas engines, four-stroke engines, two-stroke engines, and rotary engines. The engine oil can be placed into the crank case of the engine to provide the necessary lubrication and cooling effect for the engine during normal operation. The low KV100, coupled with the CCSV of the oil enabled by the use of the base stock makes it particularly fuel efficient. The engine oils are particularly advantageous as passenger vehicle engine oil (PVEO) products.

Dimer Base Stocks of the Lubricating Oil Compositions of this Disclosure

The lubricating oil compositions of this disclosure include a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) (referred to as the base stock of this disclosure) produced by dimerization and trimerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, as the monomer in the presence of a Lewis acid catalyst such as BF₃. The base stock of this disclosure can be substantially unsaturated or substantially saturated. Preferably, the base stock of this disclosure is substantially saturated, especially if it is intended for use in lubricating oil compositions, heat transfer oils, and hydraulic oils desired to have a long service life. If unsaturated, at least some of the dimer and/or trimer molecules comprise a carbon-carbon double bond, which are highly reactive and can cause instability to the base stock during use. The reactivity of such carbon-carbon double bonds can make such unsaturated base stock useful as intermediates for making other chemical materials by reacting with functionalizing agents to produce, among others, functionalized dimers and/or trimers.

The base stock of this disclosure can be advantageously substantially free of the C14 and/or C16 monomer(s) and the hydrogenated alkanes thereof. Such monomers and hydrogenated alkanes thereof, if present in the base stock at high quantity, can cause the base stock to have a high Noack volatility, which is highly undesirable.

The dimer molecules in the base stock of this disclosure are typically branched hydrocarbons, preferably branched alkanes, having a long carbon backbone. Thus, for the dimer molecules derived from two C14 mono-olefin molecules, the long carbon backbone can comprise, e.g., 20, 21, 22, 23, 24, 24, 25, 26, or 27 carbon atoms. For dimer molecules derived from two C16 mono-olefin molecules, the long carbon backbone can comprise, e.g., 24, 25, 26, 27, 28, 29, 30, or 31 carbon atoms. For dimer molecules derived from one C14 mono-olefin molecule and one C16 mono-olefin molecule, the long carbon backbone can comprise, e.g., 22, 23, 24, 25, 26, 27, 28, or 29 carbon atoms. The dimer molecules can comprise one or more branches connected to the carbon backbone. The dimer molecules of the base stock of this disclosure comprise, on average per molecule, more than one (1) branches connected to the carbon backbone. Preferably, the dimer molecules of the base stock of this disclosure comprise, on average per molecule, less than two (2) branches connected to the carbon backbone. Preferably, the dimer molecule of the base stock of this disclosure comprises, on average per molecule, from 1.1 to 1.9 branches, 1.2 to 1.8 branches, 1.3 to 1.7 branches, 1.4 to 1.6 branches, or 1.5 to 1.6 branches. Average number of branches in an alkane material can be determined using ¹³C NMR. Compared to the dimer molecule of 1-tetradecene made by coordination insertion oligomerization using a metallocene catalyst, the dimer molecules in the base stock of this disclosure tend to have significantly higher number of branches on average per molecule. Without intending to be bound by a particular theory, it is believed this is due to the use of Lewis acid catalyst such as BF₃ in the process of making the material, which simultaneously catalyzes the oligomerization reactions between the monomer molecules, the isomerization of the monomer molecules and other reactions, leading to multiple branches with various length in the dimer molecules. On the other hand, compared to the trimer molecules of 1-decene made by oligomerization catalyzed by similar Lewis-acid catalyst such as BF₃, the dimer molecules in the base stock of this disclosure tend to have significantly higher linearity characterized by a longer carbon backbone and much fewer branches connected to the carbon backbone. The significantly higher linearity renders the dimer molecules in the base stock of this disclosure significantly waxier than the 1-decene trimer molecules, which is believed to cause many surprising, interesting and advantageous lubricant properties of the base stocks of this disclosure, as the Examples section of this disclosure clearly demonstrates.

The trimer molecules in the base stock of this disclosure are branched hydrocarbons, preferably branched alkanes. Because they are produced from the oligomerization of three monomer molecules, they tend to have, on average per molecule, higher number of branches connected to the carbon backbone therein than the dimers. It is believed that the trimers in the base stock of this disclosure resembles the molecular structures of the trimers made from C8-C12 linear alpha-olefins in conventional low-viscosity base stocks commercially available discussed above.

The base stock of this disclosure preferably comprises predominantly dimers. Thus, the base stock of this disclosure can comprise the dimers at a concentration in the range from c1 to c2 wt %, based on the total weight of the base stock, where c1 and c2 can be, independently: 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100, as long as c1<c2. Preferably c1=80 and c2=100; more preferably c1=82 and c2=99; still more preferably c1=85 and c2=98, still more preferably c1=86 and c2=96, still more preferably c1=88 and c2=95, and still more preferably c1=90 and c2=94. For the base stocks made from the same monomer composition, the higher the concentration of the dimers, the lower the KV100 of the base stock tends to be.

The base stock of this disclosure, including but not limited to those having the feature(s) described above, can preferably comprise the trimers as a minor component. Thus, the base stock of this disclosure can comprise the trimers at a concentration in the range from c3 to c4 wt %, based on the total weight of the base stock, where c3 and c4 can be, independently: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, as long as c3<c4. Preferably c3=0 and c4=20; more preferably c3=2 and c4=18; still more preferably c3=4 and c4=16, still more preferably c3=5 and c4=85, still more preferably c3=5 and c4=86; still more preferably c3=5 and c4=88; and still more preferably c3=5 and c4=90. For the base stocks made from the same monomer composition, the higher the concentration of the trimers, the higher the KV100 of the base stock tends to be. A high concentration of dimers in the base stock of this disclosure imparts very interesting lubricant properties to the base stocks of this disclosure surprisingly suitable for formulating high-quality low-viscosity engine oils, especially those in the 0W grade.

The base stock of this disclosure, including but not limited to those having the feature(s) described above, can preferably comprise the dimers and trimers combined at a total concentration thereof of at least 95 wt %, or at least 96 wt %, or at least 97 wt %, or at least 98 wt %, or at least 99 wt %, or at least 99.5 wt %, or at least even 99.9 wt %, based on the total weight of the base stock.

The base stock of this disclosure, including but not limited to those having the feature(s) described above, preferably comprises a C56-C64 hydrocarbon fraction (“tetramers”) and hydrocarbon fractions with even larger number of carbon atoms in molecules thereof, if any at all, at a total concentration thereof no higher than 5 wt %, preferably no higher than 4 wt %, more preferably no higher than 3 wt %, still more preferably no higher than 2 wt %, still more preferably no higher than 1 wt %, still more preferably no higher than 0.8 wt %, still more preferably no higher than 0.5 wt %, still more preferably no higher than 0.1 wt %, based on the total weight of the base stock. A high concentration of the tetramers can lead to a high kinematic viscosity at 100° C. of the base stock, which can be undesirable for formulating low-viscosity lubricants.

The base stock of this disclosure, including but not limited to those having the feature(s) described above, can desirably exhibit a pour point determined pursuant to ASTM D5950 in the range from −45 to −10° C., preferably in the range from −40 to −15° C., more preferably from −40 to −20° C., still more preferably from −40 to −25° C., still more preferably from −40 to −30° C., still more preferably from −40 to −35° C. Compared to other low-viscosity Group IV base stocks made from C8-C12 linear alpha-olefin monomer(s) by Lewis-acid catalyzed oligomerization reactions (“conventional low-viscosity PAO base stocks”) having similar kinematic viscosity at 100° C., the base stocks of this disclosure exhibit significantly higher pour points, as demonstrated by the examples section of this disclosure. However, surprisingly, the high pour points of the base stocks of this disclosure do not prevent them from blending successfully with conventional PAO base stocks to form high-quality, low-viscosity engine oils.

The base stocks of this disclosure, including but not limited to those having the feature(s) described above, can desirably exhibit a kinematic viscosity at 100° C. determined pursuant to ASTM D445 in the range from 3.0 to 5.0 cSt, preferably from 3.2 to 4.8 cSt, more preferably from 3.3 to 4.5 cSt, still more preferably from 3.4 to 4.2 cSt, and still more preferably from 3.5 to 4.0 cSt. The low KV100 of these base stocks of this disclosure render them particularly suitable as candidate for primary base stock and/or co-base stocks useful for engine oils and other lubricants requiring a low KV100 for the formulation.

The base stocks of this disclosure, including but not limited to those having the feature(s) described above, can desirably exhibit a high viscosity index in the range from 120 to 170, preferably from 125 to 165, more preferably from 130 to 160, still more preferably from 135 to 155. As shown in the Examples section of this disclosure, compared to conventional low-viscosity PAO base stocks, the base stocks of this disclosure tend to have significantly higher viscosity index, which is highly desirable for engine oils and other lubricant products, as well as heat transfer oils and hydraulic oils.

The base stocks of this disclosure, including but not limited to those having the feature(s) described above, can desirably exhibit a Noack volatility determined pursuant to ASTM D5800 no higher than 20 wt %, preferably no higher than 18 wt %, more preferably no higher than 17 wt %, and still more preferably no higher than 15 wt %.

The base stocks of this disclosure, including but not limited to those having the feature(s) described above, can desirably exhibit the following properties when blended with a conventional polyalphaolefin base stock made from C8-C12 linear alphaolefin feed by Lewis acid catalysis having a KV100 of about 4.0 cSt (e.g., in the range from 4.0 to 4.2 cSt), a pour point at most −50° C. (preferably at most −60° C., still more preferably at most −65° C.) (“PAO reference base stock”), to form a first mixture oil comprising the base stock based on the total weight of the first mixture oil, a second mixture oil comprising 20 wt % of the base stock based on the total weight of the second mixture oil, and a third mixture oil comprising 30 wt % of the base stock based on the total weight of the base stock, at least one of the following is met: (i) the first mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock; (ii) the second mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock; and (iii) the third mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock. Preferably at least one of the following is met: (i) the first mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock; (ii) the second mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock; and (iii) the third mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock. Preferably, the base stock exhibits a CCSV at −35° C. higher than that of the PAO reference base stock. In certain embodiments, the base stock preferably exhibits a CCSV at −35° C. higher than 2000 mPa·s. Even though the base stock in neat form exhibits such a high CCSV at −35° C., its binary mixtures with the PAO reference base stock nonetheless can exhibit a CCSV at −35° C. lower than that of the PAO reference base stock and that of the base stock itself. This interesting CCSV behavior of the base stock of this disclosure is very surprising. In other embodiments, the base stock of this disclosure can exhibit a CCSV at −35° C. of lower than 1000 mPa·s (e.g., a base stock comprising at least 90 wt % of dimers of C14 linear alpha-olefins), such low CCSV at −35° C. of such base stock of this disclosure is conducive to a CCSV at −35° C. of the mixtures comprising it and the PAO reference base stock. The CCSV-lowering behavior of the base stock of this disclosure can be observed as well when mixed with conventional low-viscosity PAO base stocks with other viscosities, such as about 5, 6, 7, 8, 9, or 10 cSt, or even with Group II and III base stocks. The CCSV-lowering behavior of the base stock of this disclosure when combined with conventional low-viscosity PAO base stocks and Group II or III base stocks renders it particularly advantageous in formulating engine oils in the 0W grade and other winter grades as a co-base stock with a primary conventional low-viscosity PAO base stock or Group II or III base stock.

Method for Making the Dimer Base Stock of This Disclosure

The base stock of this disclosure is made by oligomerization of a C14 linear mono-olefin, a C16 linear mono-olefin, or a mixture of a C14 and C16 linear mono-olefin in the presence of a catalyst system comprising a Lewis acid such as BF₃ or AlCl₃. The process preferably comprises the following steps: (I) providing an olefin monomer feed comprising a C14 linear mono-olefin, a C16 linear mono-olefin, or a mixture thereof; (II) contacting the olefin monomer(s) with a catalyst system comprising a Lewis acid in at least one oligomerization reactor under oligomerization conditions to obtain an oligomerization reaction mixture comprising unreacted olefin monomer(s), dimers, trimers, and the catalyst system; (III) quenching the oligomerization reaction mixture; (IV) removing the unreacted monomer(s) from the quenched oligomerization reaction mixture after step (III) to obtain an unsaturated product precursor; and (V) optionally hydrogenating the unsaturated product precursor in a hydrogenation reactor in the presence of hydrogen under hydrogenation conditions to obtain a hydrogenated oligomer oil; and (VI) obtaining the base stock comprising dimers and optionally trimers from the unhydrogenated product precursor or hydrogenated dimers and optionally hydrogenated trimers from the hydrogenated oligomer oil. In an alternative process, step (V) of hydrogenating the unsaturated product precursor is omitted, and the base stock comprising unsaturated dimers and unsaturated trimers can be obtained directly from the unsaturated product precursor. In one specific embodiment, the unsaturated product precursor comprising the unsaturated dimers and trimers can be used as the base stock of this disclosure as is. Preferably the process for making the base stock of this disclosure includes steps (V) and (VI) above, and the thus-produced base stock comprises saturated dimers and trimers.

The C14 linear mono-olefin can be 1-tetradecene, 2-tetradecene, 3-tetradecene, 4-tetradecene, 5-tetradecene, or 6-tetradecene, or any mixture of two or more thereof, preferably 1-tetradecene. 1-tetradecene is an alpha-olefin; and the rest internal mono-olefins. Commercially available 1-tetradecene typically contain some internal C14 mono-olefins above as impurities. In the oligomerization step (II) above, in the presence of a strong Lewis acid such as BF₃, 1-tetradecene may isomerize to form one or more of the internal olefins at various concentrations thereof, which can undergo dimerization and/or trimerization reactions with each other and other mono-olefin monomers to form the oligomerization reaction mixture comprising the monomers and isomers thereof, dimers, trimers, and higher oligomers.

The C16 linear mono-olefin can be 1-hexadecene, 2-hexadecene, 3-hexadecene, 4-hexadecene, 5-hexadecene, 6-hexadecene, or 7-hexadecene, or any mixture of two or more thereof, preferably 1-hexadecene. While 1-hexadecene is an alpha-olefin, the rest are internal mono-olefins. Commercially available 1-hexadecene typically contain some internal C16 mono-olefins above as impurities. In the oligomerization step (II) above, in the presence of a strong Lewis acid such as BF₃, 1-hexadecene may isomerize to form one or more of the internal olefins at various concentrations thereof, which can undergo dimerization and/or trimerization reactions with each other and other mono-olefin monomers to form the oligomerization reaction mixture comprising the monomers and isomers thereof, dimers, trimers, and higher oligomers.

The oligomerization reactor in step (II) can be a batch reactor, a semibatch reactor, or a continuous reactor, but preferably a continuous reactor such as a continuously stirred tank reactor (“CSTR”). The reactor can include a single vessel, multiple vessels arranged in parallel, or multiple vessels arranged in series. In a preferred embodiment, in step (II) the reactor is a continuous reactor including two reaction vessels connected in series, wherein the monomers are all charged into the upstream vessel where oligomerization reactions proceed for a first residence time, and the effluent from the upstream vessel is fed into the downstream vessel where oligomerization reactions proceed for a second residence time to produce the oligomerization reaction mixture discharged from the second vessel.

The catalyst system used in the reactor in step (II) includes a Lewis acid such as BF₃ and AlCl₃, with BF₃ preferred. Where BF₃ is used, the catalyst system typically further includes a promoter system including an alcohol and optionally an ester. Such alcohol useful in the promoter system include examples such as ethanol, n-propanol, n-butanol, n-pentanol, and the like. Such ester useful in the promoter system include examples such as ethyl acetate, n-butyl acetate, and the like. Many of the alcohols and esters and combinations thereof described in U.S. Pat. No. 7,544,850 can be used in the oligomerization step (II) of the process of this disclosure. Among these, the combination of ethanol and ethyl acetate was found to be most preferred for making a base stock of this disclosure comprising dimers as a predominant component (e.g., comprising dimers at a concentration at least 80 wt % based on the total weight of the base stock) in that it results in a high conversion of the C14 and C16 monomer(s) in the reaction, and a high selectivity toward dimers over trimers and higher oligomers. When ethanol/ethyl acetate combination is used as the promoter for BF₃, one can achieve the production of a base stock comprising predominantly dimers without having to separate the dimers from higher oligomers in a distillation step after the removal of monomers in step (IV). When other promoter systems, e.g., butanol/butyl acetate, are used, the selectivity toward trimers and higher oligomers such as tetramers tend to be much higher than when ethanol/ethyl acetate is used, sometimes necessitating a step of separating the dimers from such higher oligomers by distillation after step (IV) in order to produce a base stock comprising dimers as a predominant component.

When a catalyst system comprising BF₃, ethanol and ethyl acetate is used, preferably the molar ratio of the monomer feed to BF₃ is in the range from 2 to 20, more preferably from 2.5 to 13.5, still more preferably from 3.4 to 10.1, still more preferably from 4 to 10.1, still more preferably from 4.5 to 9 and still more preferably from 5 to 8. Preferably the reaction vessel(s) houses an atmosphere comprising BF₃ gas at an absolute partial pressure thereof in a range from 3.4 to 170 kilopascal (“kPa”), more preferably from 14 to 100 kPa, still more preferably from 27 to 69 kPa, and still more preferably from 31 to 37 kPa. Preferably the molar ratio of BF₃ to ethanol is in the range from 0.5 to 2.0, more preferably from 0.7 to 2.0, still more preferably from 1 to 2.0, still more preferably from 1.75 to 2.0, and still more preferably from 1.9 to 2.0. Preferably the molar ratio of ethanol to ethyl acetate is in the range from 1 to 3, more preferably from 1 to 2, still more preferably from 1 to 1.5, still more preferably from 1 to 1.25, still more preferably about 1. Where the oligomerization reactor comprises two reaction vessels in series, preferably both vessels house atmosphere having substantially the same partial pressure of BF₃, and fresh alcohol and ester, if any, are supplied only to the upstream vessel and carried forward to the second vessel. Such two-reactor arrangement is particularly advantageous in that it promotes a high selectivity toward dimers and a high overall conversion of the monomers in the oligomerization reactions.

The preferred total residence time of the olefin monomer feed in the oligomerization reactor can range from 1 to 20 hours, more preferably from 1.5 to 15 hours, still more preferably from 2 to 12.5 hours, still more preferably from 3 to 10 hours, and still more preferably from 4 to 9 hours. Where two reaction vessels are included in the oligomerization reactor, the residence time in the upstream and downstream vessels can be the same or different. The preferred ratio of residence time in the upstream reaction vessel to the residence time in the downstream reaction vessel can be in the range from 5 to 1 more preferably from 4 to 1 still more preferably from 3 to 1.

The reaction temperature in the oligomerization reactor can be preferably in the range from 10 to 100° C., more preferably from 20 to 80° C., still more preferably from 35 to 65° C., still more preferably from 40 to 60° C., still more preferably from 45 to 55° C. Where the oligomerization reactor comprises two reaction vessels in series, the reaction temperatures in the two vessels can be both in the above ranges and can be the same or different.

As described above, on contact with BF₃, a strong Lewis acid, the monomer olefin molecule(s) in the olefin monomer feed can undergo isomerization reactions to produce other olefins, particularly internal olefins if the feed is a linear alpha olefin. The olefin monomer molecules can react with each other and their isomers to produce dimer molecules with various carbon backbones having various branches. Compared to dimers made from linear alpha-olefin molecules in the presence of a coordination insertion polymerization catalyst such as a metallocene catalyst system, the dimers produced in the process of this disclosure tend to have more branches connected to the carbon backbone. Thus, the dimer molecules produced in the process of this disclosure comprise, on average per dimer molecule, more than one (1) branches connected to the carbon backbone. Some of the dimer molecules may comprise only one (1) branch connected to the carbon backbone, some comprise two (2), and a fraction may comprise more than two (2). Nonetheless, preferably, the dimer molecules produced in the oligomerization reactor comprise, on average per molecule, at most 2 branches connected to the carbon backbone. The relatively low branching and the relatively long carbon backbones of the dimer molecules result in relatively high linearity of the molecules, and a relatively high waxiness and relatively high pour point to a base stock of this disclosure comprising predominantly dimers, as discussed above.

The dimer molecules as produced in the oligomerization reactor are mono-olefins per se comprising a carbon-carbon double bond. In the presence of BF₃, the dimer molecules can isomerize to form terminal or internal olefins. Some of the dimer molecules or isomers thereof may further react with one additional monomer molecule to form trimer molecules. Some of the dimer molecules or isomers thereof may react with each other to form tetramer molecules. The trimer molecules may react with one additional monomer molecule to form tetramers. Higher oligomers than tetramers can be formed as well. On average, the higher the degree of polymerization required for producing an oligomer, the higher the number of branches connected to the carbon backbone of the oligomer molecule. Thus, on average, tetramers comprise higher number of branches connected to their carbon backbones than trimers, which, in turn, comprise higher number of branches connected to their backbones than dimers. The higher branching of trimers than dimers leads to less linearity of the trimer molecules than the dimer molecules, hence less waxiness thereof.

The oligomerization reaction mixture exiting or taken out of the oligomerization reactor is a mixture comprising unreacted olefin monomer(s), isomers of the olefin monomer(s), dimers of the olefin monomer(s), trimers of the olefin monomer(s), and higher oligomers such as tetramers, and the catalyst system comprising BF₃ and the promoter(s). The oligomerization reaction mixture can be quenched by adding an excessive quantity of the promoter, or an alkaline aqueous solution such as NaOH aqueous solution, to deactivate the BF₃ catalyst.

The quenched oligomerization reaction mixture can then be distilled to remove the unreacted monomer(s) and isomers thereof and the residual alcohol/ester promoters to yield an unsaturated product precursor. While the unsaturated product precursor can be used as a base stock per se given its lubricant properties, it is preferred that the unsaturated product precursor is hydrogenated in a hydrogenation reactor in the presence of hydrogen under hydrogenation conditions to obtain a hydrogenated oligomer oil that is substantially completely saturated, i.e., substantially all of carbon-carbon double bonds in the oligomer molecules have been hydrogenated. Such hydrogenation conditions can include the presence of a hydrogenation catalyst comprising metals such as Fe, Co, Ni, Re, Pd, Pt, Rh, Ru, and the like. A preferred hydrogenation catalyst is Raney nickel. Filtration of the catalyst particles from the hydrogenation reaction mixture exiting the hydrogenation reactor yields a hydrogenated oligomer oil. The hydrogenated oligomer oil, comprising saturated dimers and optionally trimers and higher oligomers, can be used directly as a base stock. Alternatively, the hydrogenated oligomer oil may be further separated by distillation to obtain fractions rich in dimers, trimers, or higher oligomers, which can be used as base stocks of various viscosity grades.

Examples of techniques that can be employed to characterize the base stock described above include, but are not limited to, analytical gas chromatography, nuclear magnetic resonance, thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry, differential scanning calorimetry (DSC), and volatility and viscosity measurements.

Other Lubricating Oil Base Stocks in the Lubricating Oil

A wide range of other lubricating oil base stocks known in the art can be used in conjunction with the dimer base stock in the lubricating oil compositions of the instant disclosure as primary base stock or co-base stock. Such other base stocks can be either derived from natural resources or synthetic, including un-refined, refined, or re-refined oils. Un-refined oil base stocks include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from a natural source (such as plant matters and animal tissues) or directly from a chemical esterification process. Refined oil base stocks are those un-refined base stocks further subjected to one or more purification steps such as solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation to improve the at least one lubricating oil property. Re-refined oil base stocks are obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock.

Groups I, II, III, IV and V are broad base oil stock categories developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org) to create guidelines for lubricant base oils. Group I base stocks have a viscosity index of between about 80 to 120 and contain greater than about 0.03% sulfur and/or less than about 90% saturates. Group II base stocks have a viscosity index of between about 80 to 120, and contain less than or equal to about 0.03% sulfur and greater than or equal to about 90% saturates. Group III stocks have a viscosity index greater than about 120 and contain less than or equal to about 0.03% sulfur and greater than about 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base stock includes base stocks not included in Groups I-IV. The table below summarizes properties of each of these five groups.

Base Oil Properties Saturates Sulfur Viscosity Index Group I   <90 and/or  >0.03% and ≥80 and <120 Group II ≥90 and ≤0.03% and ≥80 and <120 Group III ≥90 and ≤0.03% and ≥120 Group IV polyalphaolefins (PAO) Group V All other base oil stocks not included in Groups I, II, III or IV

Natural oils include animal oils, vegetable oils (castor oil and lard oil, for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. Of the natural oils, mineral oils are preferred. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefined, or solvent extracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks, including synthetic oils such as alkyl aromatics and synthetic esters are also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils such as polymerized and interpolymerized olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alphaolefin copolymers, for example). Polyalphaolefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from C₈, C₁₀, C₁₂, C₁₄ olefins or mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, typically vary from about 250 to about 3,000, although PAO's may be made in viscosities up to about 150 cSt (100° C.). The PAOs are typically comprised of relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include, but are not limited to, C₂ to about C₃₂ alphaolefins with the C₈ to about C₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like, being preferred. The preferred polyalphaolefins are poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures thereof and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of C₁₄ to C₁₈ may be used to provide low viscosity base stocks of acceptably low volatility. Depending on the viscosity grade and the starting oligomer, the PAOs may be predominantly trimers and tetramers of the starting olefins, with minor amounts of the higher oligomers, having a viscosity range of 1.5 to 12 cSt. PAO fluids of particular use may include 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof. Mixtures of PAO fluids having a viscosity range of 1.5 to approximately 150 cSt or more may be used if desired.

The PAO fluids may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example the methods disclosed by U.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C14 to C18 olefins are described in U.S. Pat. No. 4,218,330.

Other useful lubricant oil base stocks include wax isomerate base stocks and base oils, comprising hydroisomerized waxy stocks (e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker bottoms, etc.), hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocks and base oils, and other wax isomerate hydroisomerized base stocks and base oils, or mixtures thereof. Fischer-Tropsch waxes, the high boiling point residues of Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with very low sulfur content. The hydroprocessing used for the production of such base stocks may use an amorphous hydrocracking/hydroisomerization catalyst, such as one of the specialized lube hydrocracking (LHDC) catalysts or a crystalline hydrocracking/hydroisomerization catalyst, preferably a zeolitic catalyst. For example, one useful catalyst is ZSM-48 as described in U.S. Pat. No. 5,075,269, the disclosure of which is incorporated herein by reference in its entirety. Processes for making hydrocracked/hydroisomerized distillates and hydrocracked/hydroisomerized waxes are described, for example, in U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Each of the aforementioned patents is incorporated herein in their entirety. Particularly favorable processes are described in European Patent Application Nos. 464546 and 464547, also incorporated herein by reference. Processes using Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172 and 4,943,672, the disclosures of which are incorporated herein by reference in their entirety.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized (wax isomerate) base oils be advantageously used in the instant disclosure, and may have useful kinematic viscosities at 100° C. of about 3 cSt to about 50 cSt, preferably about 3 cSt to about 30 cSt, more preferably about 3.5 cSt to about 25 cSt, as exemplified by GTL 4 with kinematic viscosity of about 4.0 cSt at 100° C. and a viscosity index of about 141. These Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized base oils may have useful pour points of about −20° C. or lower, and under some conditions may have advantageous pour points of about −25° C. or lower, with useful pour points of about −30° C. to about −40° C. or lower. Useful compositions of Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and wax-derived hydroisomerized base oils are recited in U.S. Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and are incorporated herein in their entirety by reference.

The hydrocarbyl aromatics can be used as a base oil or base oil component and can be any hydrocarbyl molecule that contains at least about 5% of its weight derived from an aromatic moiety such as a benzenoid moiety or naphthenoid moiety, or their derivatives. These hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like. The aromatic can be mono-alkylated, dialkylated, polyalkylated, and the like. The aromatic can be mono- or poly-functionalized. The hydrocarbyl groups can also be comprised of mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl groups and other related hydrocarbyl groups. The hydrocarbyl groups can range from about C₆ up to about C₆₀ with a range of about C₈ to about C₂₀ often being preferred. A mixture of hydrocarbyl groups is often preferred, and up to about three such substituents may be present. The hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen containing substituents. The aromatic group can also be derived from natural (petroleum) sources, provided at least about 5% of the molecule is comprised of an above-type aromatic moiety. Viscosities at 100° C. of approximately 3 cSt to about 50 cSt are preferred, with viscosities of approximately 3.4 cSt to about 20 cSt often being more preferred for the hydrocarbyl aromatic component. In one embodiment, an alkyl naphthalene where the alkyl group is primarily comprised of 1-hexadecene is used. Other alkylates of aromatics can be advantageously used. Naphthalene or methyl naphthalene, for example, can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, and the like. Useful concentrations of hydrocarbyl aromatic in a lubricant oil composition can be about 2% to about 25%, preferably about 4% to about 20%, and more preferably about 4% to about 15%, depending on the application.

Alkylated aromatics such as the hydrocarbyl aromatics of the present disclosure may be produced by well-known Friedel-Crafts alkylation of aromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York, 1963. For example, an aromatic compound, such as benzene or naphthalene, is alkylated by an olefin, alkyl halide or alcohol in the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many homogeneous or heterogeneous, solid catalysts are known to one skilled in the art. The choice of catalyst depends on the reactivity of the starting materials and product quality requirements. For example, strong acids such as AlCl₃, BF₃, or HF may be used. In some cases, milder catalysts such as FeCl₃ or SnCl₄ are preferred. Newer alkylation technology uses zeolites or solid super acids.

Esters comprise a useful base stock. Additive solvency and seal compatibility characteristics may be secured by the use of esters such as the esters of dibasic acids with monoalkanols and the polyol esters of monocarboxylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters are those which are obtained by reacting one or more polyhydric alcohols, preferably the hindered polyols (such as the neopentyl polyols, e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, pentaerythritol and dipentaerythritol) with alkanoic acids containing at least about 4 carbon atoms, preferably C₅ to C₃₀ acids such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures of any of these materials.

Suitable synthetic ester components include the esters of trimethylol propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or dipentaerythritol with one or more monocarboxylic acids containing from about 5 to about 10 carbon atoms. These esters are widely available commercially, for example, the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company.

Also useful are esters derived from renewable material such as coconut, palm, rapeseed, soy, sunflower and the like. These esters may be monoesters, di-esters, polyol esters, complex esters, or mixtures thereof. These esters are widely available commercially, for example, the Esterex NP 343 ester of ExxonMobil Chemical Company.

Engine oil formulations containing renewable esters are included in this disclosure. For such formulations, the renewable content of the ester is typically greater than about 70 weight percent, preferably more than about 80 weight percent and most preferably more than about 90 weight percent.

Other useful fluids of lubricating viscosity include non-conventional or unconventional base stocks that have been processed, preferably catalytically, or synthesized to provide high performance lubrication characteristics.

Non-conventional or unconventional base stocks/base oils include one or more of a mixture of base stock(s) derived from one or more Gas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate base stock(s) derived from natural wax or waxy feeds, mineral and or non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials received from coal liquefaction or shale oil, and mixtures of such base stocks.

GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, and/or degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or base oils are GTL materials of lubricating viscosity that are generally derived from hydrocarbons; for example, waxy synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks. GTL base stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range (1) separated/fractionated from synthesized GTL materials such as, for example, by distillation and subsequently subjected to a final wax processing step which involves either or both of a catalytic dewaxing process, or a solvent dewaxing process, to produce lube oils of reduced/low pour point; (2) synthesized wax isomerates, comprising, for example, hydrodewaxed or hydroisomerized cat and/or solvent dewaxed synthesized wax or waxy hydrocarbons; (3) hydrodewaxed or hydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates); preferably hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials, especially, hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxed wax or waxy feed, preferably F-T material derived base stock(s) and/or base oil(s), are characterized typically as having kinematic viscosities at 100° C. of from about 2 mm²/s to about 50 mm²/s (ASTM D445). They are further characterized typically as having pour points of −5° C. to about −40° C. or lower (ASTM D97). They are also characterized typically as having viscosity indices of about 80 to about 140 or greater (ASTM D2270).

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than about 10 ppm, and more typically less than about 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorus and aromatics make this materially especially suitable for the formulation of low SAP products.

The term GTL base stock and/or base oil and/or wax isomerate base stock and/or base oil is to be understood as embracing individual fractions of such materials of wide viscosity range as recovered in the production process, mixtures of two or more of such fractions, as well as mixtures of one or two or more low viscosity fractions with one, two or more higher viscosity fractions to produce a blend wherein the blend exhibits a target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s) is/are derived is preferably an F-T material (i.e., hydrocarbons, waxy hydrocarbons, wax).

Base oils for use in the formulated lubricating oils useful in the present disclosure are any of the variety of oils corresponding to API Group I, Group II, Group III, Group IV, and Group V oils and mixtures thereof, preferably API Group II, Group III, Group IV, and Group V oils and mixtures thereof, more preferably the Group III to Group V base oils due to their exceptional volatility, stability, viscometric and cleanliness features. Minor quantities of Group I stock, such as the amount used to dilute additives for blending into formulated lube oil products, can be tolerated but should be kept to a minimum, i.e. amounts only associated with their use as diluent/carrier oil for additives used on an “as-received” basis. Even in regard to the Group II stocks, it is preferred that the Group II stock be in the higher quality range associated with that stock, i.e. a Group II stock having a viscosity index in the range 100<VI<120. Groups II and III base stocks can be included in the lubricating oil formulations of this disclosure, but preferably only those with high quality, e.g., those having a VI from 100 to 120. Group IV and V base stocks, preferably those of high quality, are desirably included into the lubricating oil formulations of this disclosure.

The base oil constitutes the major component of the lubricating oil compositions of the present disclosure and typically is present in an amount ranging from about 5 to about 99 weight percent, or about 7 to about 95 weight percent, or about 10 to about 90 weight percent, or about 20 to about 80 weight percent, preferably from about 70 to about 95 weight percent, and more preferably from about 85 to about 95 weight percent, based on the total weight of the composition. The base oil may be selected from any of the synthetic or natural oils typically used as crankcase lubricating oils for spark-ignited and compression-ignited engines. The base oil conveniently has a kinematic viscosity, according to ASTM standards, of about 2.5 cSt to about 12 cSt (or mm²/s) at 100° C. and preferably of about 2.5 cSt to about 9 cSt (or mm²/s) at 100° C. Mixtures of synthetic and natural base oils may be used if desired. Bi-modal mixtures of Group I, II, III, IV, and/or V base stocks may be used if desired. A second base stock or co-base stock may be also optionally incorporated into the lubricating oil compositions of this disclosure in an amount ranging from about 5 to about 80 weight percent, or about 10 to about 60 weight percent, or about 15 to about 50 weight percent, or about 20 to about 40 weight percent, or from about 25 to about 35 weight percent.

Lubricating Oil Additives of the Lubricating Oil Compositions of this Disclosure

The lubricating oil compositions (preferably lubricating oil formulations) of this disclosure may additionally contain one or more of the commonly used lubricating oil performance additives including but not limited to dispersants, detergents, viscosity modifiers, antiwear additives, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, viscosity modifiers, fluid-loss additives, seal compatibility agents, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. For a review of many commonly used additives and the quantities used, see: (i) Klamann in Lubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0; (ii) “Lubricant Additives,” M. W. Ranney, published by Noyes Data Corporation of Parkridge, N J (1973); (iii) “Synthetics, Mineral Oils, and Bio-Based Lubricants,” Edited by L. R. Rudnick, CRC Taylor and Francis, 2006, ISBN 1-57444-723-8; (iv) “Lubrication Fundamentals”, J. G. Wills, Marcel Dekker Inc., (New York, 1980); (v) Synthetic Lubricants and High-Performance Functional Fluids, 2nd Ed., Rudnick and Shubkin, Marcel Dekker Inc., (New York, 1999); and (vi) “Polyalphaolefins,” L. R. Rudnick, Chemical Industries (Boca Raton, Fla., United States) (2006), 111 (Synthetics, Mineral Oils, and Bio-Based Lubricants), 3-36. Reference is also made to: (a) U.S. Pat. No. 7,704,930 B2; (b) U.S. Pat. No. 9,458,403 B2, Column 18, line 46 to Column 39, line 68; (c) U.S. Pat. No. 9,422,497 B2, Column 34, line 4 to Column 40, line 55; and (d) U.S. Pat. No. 8,048,833 B2, Column 17, line 48 to Column 27, line 12, the disclosures of which are incorporated herein in its entirety. These additives are commonly delivered with varying amounts of diluent oil that may range from 5 wt % to 50 wt % based on the total weight of the additive package before incorporation into the formulated oil.

Further details of the lubricating oil additives useful in the lubricating oil compositions of this disclosure are as follows:

Friction Modifiers

A friction modifier is any material or materials that can alter the coefficient of friction of a surface lubricated by any lubricant or fluid containing such material(s). Friction modifiers, also known as friction reducers, or lubricity agents or oiliness agents, and other such agents that change the ability of base oils, formulated lubricant compositions, or functional fluids, to modify the coefficient of friction of a lubricated surface may be effectively used in combination with the base oils or lubricant compositions of the present disclosure if desired. Friction modifiers that lower the coefficient of friction are particularly advantageous in combination with the base oils and lube compositions of this disclosure.

Illustrative friction modifiers may include, for example, inorganic compounds or to materials, or mixtures thereof. Illustrative inorganic friction modifiers useful in the lubricating engine oil formulations of this disclosure include, for example, molybdenum amine, molybdenum diamine, an organotungstenate, a molybdenum dithiocarbamate, molybdenum dithiophosphates, molybdenum amine complexes, molybdenum carboxylates, and the like, and mixtures thereof. Similar tungsten based compounds may be preferable.

Other illustrative friction modifiers useful in the lubricating engine oil formulations of this disclosure include, for example, alkoxylated fatty acid esters, alkanolamides, polyol fatty acid esters, borated glycerol fatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include, for example, polyoxyethylene stearate, fatty acid polyglycol ester, and the like. These can include polyoxypropylene stearate, polyoxybutylene stearate, polyoxyethylene isosterate, polyoxypropylene isostearate, polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include, for example, lauric acid diethylalkanolamide, palmic acid diethylalkanolamide, and the like. These can include oleic acid diethyalkanolamide, stearic acid diethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylated hydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include, for example, glycerol mono-oleate, saturated mono-, di-, and tri-glyceride esters, glycerol mono-stearate, and the like. These can include polyol esters, hydroxyl-containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include, for example, borated glycerol mono-oleate, borated saturated mono-, di-, and tri-glyceride esters, borated glycerol mono-sterate, and the like. In addition to glycerol polyols, these can include trimethylolpropane, pentaerythritol, sorbitan, and the like. These esters can be polyol monocarboxylate esters, polyol dicarboxylate esters, and on occasion polyoltricarboxylate esters. Preferred can be the glycerol mono-oleates, glycerol dioleates, glycerol trioleates, glycerol monostearates, glycerol distearates, and glycerol tristearates and the corresponding glycerol monopalmitates, glycerol dipalmitates, and glycerol tripalmitates, and the respective isostearates, linoleates, and the like. On occasion the glycerol esters can be preferred as well as mixtures containing any of these. Ethoxylated, propoxylated, butoxylated fatty acid esters of polyols, especially using glycerol as underlying polyol can be preferred.

Illustrative fatty alcohol ethers include, for example, stearyl ether, myristyl ether, and the like. Alcohols, including those that have carbon numbers from C₃ to C₅₀, can be ethoxylated, propoxylated, or butoxylated to form the corresponding fatty alkyl ethers. The underlying alcohol portion can preferably be stearyl, myristyl, C₁₁-C₁₃ hydrocarbon, oleyl, isosteryl, and the like.

Useful concentrations of friction modifiers may range from 0.01 weight percent to 5 weight percent, or about 0.1 weight percent to about 2.5 weight percent, or about 0.1 weight percent to about 1.5 weight percent, or about 0.1 weight percent to about 1 weight percent. Concentrations of molybdenum-containing materials are often described in terms of Mo metal concentration. Advantageous concentrations of Mo may range from 25 ppm to 700 ppm or more, and often with a preferred range of 50-200 ppm. Friction modifiers of all types may be used alone or in mixtures with the materials of this disclosure. Often mixtures of two or more friction modifiers, or mixtures of friction modifier(s) with alternate surface active material(s), are also desirable.

Antiwear Additives

A metal alkylthiophosphate and more particularly a metal dialkyl dithio phosphate in which the metal constituent is zinc, or zinc dialkyl dithio phosphate (ZDDP) can be a useful component of the lubricating oils of this disclosure. ZDDP can be derived from primary alcohols, secondary alcohols or mixtures thereof. ZDDP compounds generally are of the formula

Zn[SP(S)(OR¹)(OR²)]₂

where R¹ and R² are C₁-C₁₈ alkyl groups, preferably C₂-C₁₂ alkyl groups. These alkyl groups may be straight chain or branched. Alcohols used in the ZDDP can be 2-propanol, butanol, secondary butanol, pentanols, hexanols such as 4-methyl-2-pentanol, n-hexanol, n-octanol, 2-ethyl hexanol, alkylated phenols, and the like. Mixtures of secondary alcohols or of primary and secondary alcohol can be preferred. Alkyl aryl groups may also be used.

Preferable zinc dithiophosphates which are commercially available include secondary zinc dithiophosphates such as those available from for example, The Lubrizol Corporation under the trade designations “LZ 677A”, “LZ 1095” and “LZ 1371”, from for example Chevron Oronite under the trade designation “OLOA 262” and from for example Afton Chemical under the trade designation “HITEC 7169”.

The ZDDP is typically used in amounts of from about 0.4 weight percent to about 1.2 weight percent, preferably from about 0.5 weight percent to about 1.0 weight percent, and more preferably from about 0.6 weight percent to about 0.8 weight percent, based on the total weight of the lubricating oil, although more or less can often be used advantageously. Preferably, the ZDDP is a secondary ZDDP and present in an amount of from about 0.6 to 1.0 weight percent of the total weight of the lubricating oil.

Low phosphorus engine oil formulations are included in this disclosure. For such formulations, the phosphorus content is typically less than about 0.12 weight percent preferably less than about 0.10 weight percent and most preferably less than about 0.085 weight percent.

Dispersants

During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants used in the formulation of the lubricating oil may be ashless or ash-forming in nature. Preferably, the dispersant is ashless. So called ashless dispersants are organic materials that form substantially no ash upon combustion. For example, non-metal-containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents discussed herein form ash upon combustion.

Suitable dispersants typically contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the (poly)alkenylsuccinic derivatives, typically produced by the reaction of a long chain hydrocarbyl substituted succinic compound, usually a hydrocarbyl substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain hydrocarbyl group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. Exemplary U.S. patents describing such dispersants are U.S. Pat. Nos. 3,172,892; 3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A further description of dispersants may be found, for example, in European Patent Application No. 471 071, to which reference is made for this purpose.

Hydrocarbyl-substituted succinic acid and hydrocarbyl-substituted succinic anhydride derivatives are useful dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound preferably having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine are particularly useful.

Succinimides are formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and amines. Molar ratios can vary depending on the polyamine. For example, the molar ratio of hydrocarbyl substituted succinic anhydride to TEPA can vary from about 1:1 to about 5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800; and Canada Patent No. 1,094,044.

Succinate esters are formed by the condensation reaction between hydrocarbyl substituted succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of a hydrocarbyl substituted succinic anhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction between hydrocarbyl substituted succinic anhydrides and alkanol amines. For example, suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines and polyalkenylpolyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine. Representative examples are shown in U.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydrides used in the preceding paragraphs will typically range between 800 and 2,500 or more. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic acid. The above products can also be post reacted with boron compounds such as boric acid, borate esters or highly borated dispersants, to form borated dispersants generally having from about 0.1 to about 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which is incorporated herein by reference. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture. Molecular weights of the alkylphenols range from 800 to 2,500. Representative examples are shown in U.S. Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannich condensation products useful in this disclosure can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HNR₂ group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are well known to one skilled in the art; see, for example, U.S. Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

Preferred dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a Mn of from about 500 to about 5000, or from about 1000 to about 3000, or about 1000 to about 2000, or a mixture of such hydrocarbylene groups, often with high terminal vinylic groups. Other preferred dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components.

Polymethacrylate or polyacrylate derivatives are another class of dispersants. These dispersants are typically prepared by reacting a nitrogen containing monomer and a methacrylic or acrylic acid esters containing 5-25 carbon atoms in the ester group. Representative examples are shown in U.S. Pat. Nos. 2,100,993, and 6,323,164. Polymethacrylate and polyacrylate dispersants are normally used as multifunctional viscosity modifiers. The lower molecular weight versions can be used as lubricant dispersants or fuel detergents.

Illustrative preferred dispersants useful in this disclosure include those derived from polyalkenyl-substituted mono- or dicarboxylic acid, anhydride or ester, which dispersant has a polyalkenyl moiety with a number average molecular weight of at least 900 and from greater than 1.3 to 1.7, preferably from greater than 1.3 to 1.6, most preferably from greater than 1.3 to 1.5, functional groups (mono- or dicarboxylic acid producing moieties) per polyalkenyl moiety (a medium functionality dispersant). Functionality (F) can be determined according to the following formula:

F=(SAP×M_(n))/((112,200×A.I.)−(SAP×98))

wherein SAP is the saponification number (i.e., the number of milligrams of KOH consumed in the complete neutralization of the acid groups in one gram of the succinic-containing reaction product, as determined according to ASTM D94); M_(n) is the number average molecular weight of the starting olefin polymer; and A.I. is the percent active ingredient of the succinic-containing reaction product (the remainder being unreacted olefin polymer, succinic anhydride and diluent).

The polyalkenyl moiety of the dispersant may have a number average molecular weight of at least 900, suitably at least 1500, preferably between 1800 and 3000, such as between 2000 and 2800, more preferably from about 2100 to 2500, and most preferably from about 2200 to about 2400. The molecular weight of a dispersant is generally expressed in terms of the molecular weight of the polyalkenyl moiety. This is because the precise molecular weight range of the dispersant depends on numerous parameters including the type of polymer used to derive the dispersant, the number of functional groups, and the type of nucleophilic group employed.

Polymer molecular weight, specifically M_(n), can be determined by various known techniques. One convenient method is gel permeation chromatography (GPC), which additionally provides molecular weight distribution information (see W. W. Yau, J. J. Kirkland and D. D. Bly, “Modern Size Exclusion Liquid Chromatography”, John Wiley and Sons, New York, 1979). Another useful method for determining molecular weight, particularly for lower molecular weight polymers, is vapor pressure osmometry (e.g., ASTM D3592).

The polyalkenyl moiety in a dispersant preferably has a narrow molecular weight distribution (MWD), also referred to as polydispersity, as determined by the ratio of weight average molecular weight (M_(w)) to number average molecular weight (M_(n)). Polymers having a M_(w)/M_(n) of less than 2.2, preferably less than 2.0, are most desirable. Suitable polymers have a polydispersity of from about 1.5 to 2.1, preferably from about 1.6 to about 1.8.

Suitable polyalkenes employed in the formation of the dispersants include homopolymers, interpolymers or lower molecular weight hydrocarbons. One family of such polymers comprise polymers of ethylene and/or at least one C₃ to C₂ alpha-olefin having the formula H₂C═CHR¹ wherein R¹ is a straight or branched chain alkyl radical comprising 1 to 26 carbon atoms and wherein the polymer contains carbon-to-carbon unsaturation, and a high degree of terminal ethenylidene unsaturation. Preferably, such polymers comprise interpolymers of ethylene and at least one alpha-olefin of the above formula, wherein R¹ is alkyl of from 1 to 18 carbon atoms, and more preferably is alkyl of from 1 to 8 carbon atoms, and more preferably still of from 1 to 2 carbon atoms.

Another useful class of polymers is polymers prepared by cationic polymerization of monomers such as isobutene and styrene. Common polymers from this class include polyisobutenes obtained by polymerization of a C4 refinery stream having a butene content of 35 to 75% by wt., and an isobutene content of 30 to 60% by wt. A preferred source of monomer for making poly-n-butenes is petroleum feedstreams such as Raffinate II. These feedstocks are disclosed in the art such as in U.S. Pat. No. 4,952,739. A preferred embodiment utilizes polyisobutylene prepared from a pure isobutylene stream or a Raffinate I stream to prepare reactive isobutylene polymers with terminal vinylidene olefins. Polyisobutene polymers that may be employed are generally based on a polymer chain of from 1500 to 3000.

The dispersant(s) are preferably non-polymeric (e.g., mono- or bis-succinimides). Such dispersants can be prepared by conventional processes such as disclosed in U.S. Patent Application Publication No. 2008/0020950, the disclosure of which is incorporated herein by reference.

The dispersant(s) can be borated by conventional means, as generally disclosed in U.S. Pat. Nos. 3,087,936, 3,254,025 and 5,430,105.

Such dispersants may be used in an amount of about 0.01 to 20 weight percent or 0.01 to 10 weight percent, preferably about 0.5 to 8 weight percent, or more preferably 0.5 to 4 weight percent. Or such dispersants may be used in an amount of about 2 to 12 weight percent, preferably about 4 to 10 weight percent, or more preferably 6 to 9 weight percent. On an active ingredient to basis, such additives may be used in an amount of about 0.06 to 14 weight percent, preferably about 0.3 to 6 weight percent. The hydrocarbon portion of the dispersant atoms can range from C₆₀ to C₁₀₀₀, or from C₇₀ to C₃₀₀, or from C₇₀ to C₂₀₀. These dispersants may contain both neutral and basic nitrogen, and mixtures of both. Dispersants can be end-capped by borates and/or cyclic carbonates. Nitrogen content in the finished oil can vary from about 200 ppm by weight to about 2000 ppm by weight, preferably from about 200 ppm by weight to about 1200 ppm by weight. Basic nitrogen can vary from about 100 ppm by weight to about 1000 ppm by weight, preferably from about 100 ppm by weight to about 600 ppm by weight.

As used herein, the dispersant concentrations are given on an “as delivered” basis. Typically, the active dispersant is delivered with a process oil. The “as delivered” dispersant typically contains from about 20 weight percent to about 80 weight percent, or from about 40 weight percent to about 60 weight percent, of active dispersant in the “as delivered” dispersant product.

Detergents

Illustrative detergents useful in this disclosure include, for example, alkali metal detergents, alkaline earth metal detergents, or mixtures of one or more alkali metal detergents and one or more alkaline earth metal detergents. A typical detergent is an anionic material that contains a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as a sulfur-containing acid, carboxylic acid (e.g., salicylic acid), phosphorus-containing acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal. The detergent can be overbased as described herein.

The detergent is preferably a metal salt of an organic or inorganic acid, a metal salt of a phenol, or mixtures thereof. The metal is preferably selected from an alkali metal, an alkaline earth metal, and mixtures thereof. The organic or inorganic acid is selected from an aliphatic organic or inorganic acid, a cycloaliphatic organic or inorganic acid, an aromatic organic or inorganic acid, and mixtures thereof.

The metal is preferably selected from an alkali metal, an alkaline earth metal, and mixtures thereof. More preferably, the metal is selected from calcium (Ca), magnesium (Mg), and mixtures thereof.

The organic acid or inorganic acid is preferably selected from a sulfur-containing acid, a carboxylic acid, a phosphorus-containing acid, and mixtures thereof.

Preferably, the metal salt of an organic or inorganic acid or the metal salt of a phenol comprises calcium phenate, calcium sulfonate, calcium salicylate, magnesium phenate, magnesium sulfonate, magnesium salicylate, an overbased detergent, and mixtures thereof.

Salts that contain a substantially stochiometric amount of the metal are described as neutral salts and have a total base number (TBN, as measured by ASTM D2896) of from 0 to 80. Many compositions are overbased, containing large amounts of a metal base that is achieved by reacting an excess of a metal compound (a metal hydroxide or oxide, for example) with an acidic gas (such as carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly overbased. These detergents can be used in mixtures of neutral, overbased, highly overbased calcium salicylate, sulfonates, phenates and/or magnesium salicylate, sulfonates, phenates. The TBN ranges can vary from low, medium to high TBN products, including as low as 0 to as high as 600. Preferably the TBN delivered by the detergent is between 1 and 20. More preferably between 1 and 12. Mixtures of low, medium, high TBN can be used, along with mixtures of calcium and magnesium metal based detergents, and including sulfonates, phenates, salicylates, and carboxylates. A detergent mixture with a metal ratio of 1, in conjunction of a detergent with a metal ratio of 2, and as high as a detergent with a metal ratio of 5, can be used. Borated detergents can also be used.

Alkaline earth phenates are another useful class of detergent. These detergents can be made by reacting alkaline earth metal hydroxide or oxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀ or mixtures thereof. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that starting alkylphenols may contain more than one alkyl substituent that are each independently straight chain or branched and can be used from 0.5 to 6 weight percent. When a non-sulfurized alkylphenol is used, the sulfurized product may be obtained by methods well known in the art. These methods include heating a mixture of alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides such as sulfur dichloride, and the like) and then reacting the sulfurized phenol with an alkaline earth metal base.

In accordance with this disclosure, metal salts of carboxylic acids are preferred detergents. These carboxylic acid detergents may be prepared by reacting a basic metal compound with at least one carboxylic acid and removing free water from the reaction product. These compounds may be overbased to produce the desired TBN level. Detergents made from salicylic acid are one preferred class of detergents derived from carboxylic acids. Useful salicylates include long chain alkyl salicylates. One useful family of compositions is of the formula

where R is an alkyl group having 1 to about 30 carbon atoms, n is an integer from 1 to 4, and M is an alkaline earth metal. Preferred R groups are alkyl chains of at least C₁₁, preferably C₁₃ or greater. R may be optionally substituted with substituents that do not interfere with the detergent's function. M is preferably, calcium, magnesium, barium, or mixtures thereof. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of the hydrocarbyl-substituted salicylic acids may be prepared by double decomposition of a metal salt in a polar solvent such as water or alcohol.

Alkaline earth metal phosphates are also used as detergents and are known in the art.

Detergents may be simple detergents or what is known as hybrid or complex detergents. The latter detergents can provide the properties of two detergents without the need to blend separate materials. See U.S. Pat. No. 6,034,039.

Preferred detergents include calcium sulfonates, magnesium sulfonates, calcium salicylates, magnesium salicylates, calcium phenates, magnesium phenates, and other related components (including borated detergents), and mixtures thereof. Preferred mixtures of detergents include magnesium sulfonate and calcium salicylate, magnesium sulfonate and calcium sulfonate, magnesium sulfonate and calcium phenate, calcium phenate and calcium salicylate, calcium phenate and calcium sulfonate, calcium phenate and magnesium salicylate, calcium phenate and magnesium phenate. Overbased detergents are also preferred.

The detergent concentration in the lubricating oils of this disclosure can range from about 0.5 to about 6.0 weight percent, preferably about 0.6 to 5.0 weight percent, and more preferably from about 0.8 weight percent to about 4.0 weight percent, based on the total weight of the lubricating oil.

As used herein, the detergent concentrations are given on an “as delivered” basis. Typically, the active detergent is delivered with a process oil. The “as delivered” detergent typically contains from about 20 weight percent to about 100 weight percent, or from about 40 weight percent to about 60 weight percent, of active detergent in the “as delivered” detergent product.

Viscosity Modifiers

Viscosity modifiers (also known as viscosity index improvers (VI improvers), and to viscosity improvers) can be included in the lubricant compositions of this disclosure.

Viscosity modifiers provide lubricants with high and low temperature operability. These additives impart shear stability at elevated temperatures and acceptable viscosity at low temperatures.

Suitable viscosity modifiers include high molecular weight hydrocarbons, polyesters and viscosity modifier dispersants that function as both a viscosity modifier and a dispersant. Typical molecular weights of these polymers are between about 10,000 to 1,500,000, more typically about 20,000 to 1,200,000, and even more typically between about 50,000 and 1,000,000.

Examples of suitable viscosity modifiers are linear or star-shaped polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes. Polyisobutylene is a commonly used viscosity modifier. Another suitable viscosity modifier is polymethacrylate (copolymers of various chain length alkyl methacrylates, for example), some formulations of which also serve as pour point depressants. Other suitable viscosity modifiers include copolymers of ethylene and propylene, hydrogenated block copolymers of styrene and isoprene, and polyacrylates (copolymers of various chain length acrylates, for example). Specific examples include styrene-isoprene or styrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

Olefin copolymers are commercially available from Chevron Oronite Company LLC under the trade designation “PARATONE®” (such as “PARATONE® 8921” and “PARATONE® 8941”); from Afton Chemical Corporation under the trade designation “HiTEC®” (such as “HiTEC® 5850B”; and from The Lubrizol Corporation under the trade designation “Lubrizol® 7067C”. Hydrogenated polyisoprene star polymers are commercially available from Infineum International Limited, e.g., under the trade designation “SV200” and “SV600”. Hydrogenated diene-styrene block copolymers are commercially available from Infineum International Limited, e.g., under the trade designation “SV 50”.

The polymethacrylate or polyacrylate polymers can be linear polymers which are available from Evnoik Industries under the trade designation “Viscoplex®” (e.g., Viscoplex 6-954) or star polymers which are available from Lubrizol Corporation under the trade designation Asteric™ (e.g., Lubrizol 87708 and Lubrizol 87725).

Illustrative vinyl aromatic-containing polymers useful in this disclosure may be derived predominantly from vinyl aromatic hydrocarbon monomer. Illustrative vinyl aromatic-containing copolymers useful in this disclosure may be represented by the following general formula:

A-B

wherein A is a polymeric block derived predominantly from vinyl aromatic hydrocarbon to monomer, and B is a polymeric block derived predominantly from conjugated diene monomer.

In an embodiment of this disclosure, the viscosity modifiers may be used in an amount of less than about 10 weight percent, preferably less than about 7 weight percent, more preferably less than about 4 weight percent, and in certain instances, may be used at less than 2 weight percent, preferably less than about 1 weight percent, and more preferably less than about 0.5 weight percent, based on the total weight of the formulated oil or lubricating engine oil. Viscosity modifiers are typically added as concentrates, in large amounts of diluent oil.

As used herein, the viscosity modifier concentrations are given on an “as delivered” basis. Typically, the active polymer is delivered with a diluent oil. The “as delivered” viscosity modifier typically contains from 20 weight percent to 75 weight percent of an active polymer for polymethacrylate or polyacrylate polymers, or from 8 weight percent to 20 weight percent of an active polymer for olefin copolymers, hydrogenated polyisoprene star polymers, or hydrogenated diene-styrene block copolymers, in the “as delivered” polymer concentrate.

Antioxidants

Antioxidants retard the oxidative degradation of base oils during service. Such degradation may result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant. One skilled in the art knows a wide variety of oxidation inhibitors that are useful in lubricating oil compositions. See, Klamann in Lubricants and Related Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197, for example.

Useful antioxidants include hindered phenols. These phenolic antioxidants may be ashless (metal-free) phenolic compounds or neutral or basic metal salts of certain phenolic compounds. Typical phenolic antioxidant compounds are the hindered phenolics which are the ones which contain a sterically hindered hydroxyl group, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Typical phenolic antioxidants include the hindered phenols substituted with C₆+ alkyl groups and the alkylene coupled derivatives of these hindered phenols. Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered mono-phenolic antioxidants may include for example hindered 2,6-di-alkyl-phenolic proprionic ester derivatives. Bis-phenolic antioxidants may also be advantageously used in combination with the instant disclosure. Examples of ortho-coupled phenols include: 2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol); and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols include for example 4,4′-bis(2,6-di-t-butyl phenol) and 4,4′-methylene-bis(2,6-di-t-butyl phenol).

Effective amounts of one or more catalytic antioxidants may also be used. The catalytic antioxidants comprise an effective amount of a) one or more oil soluble polymetal organic compounds; and, effective amounts of b) one or more substituted N,N′-diaryl-o-phenylenediamine compounds or c) one or more hindered phenol compounds; or a combination of both b) and c). Catalytic antioxidants are more fully described in U.S. Pat. No. 8,048,833, herein incorporated by reference in its entirety.

Non-phenolic oxidation inhibitors which may be used include aromatic amine antioxidants and these may be used either as such or in combination with phenolics. Typical examples of non-phenolic antioxidants include: alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R⁸R⁹R¹⁰N where R⁸ is an aliphatic, aromatic or substituted aromatic group, R⁹ is an aromatic or a substituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)XR¹² where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R⁸ may contain from 1 to about 20 carbon atoms, and preferably contains from about 6 to 12 carbon atoms. The aliphatic group is a saturated aliphatic group. Preferably, both R⁸ and R⁹ are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic group such as naphthyl. Aromatic groups R⁸ and R⁹ may be joined together with other groups such as S.

Typical aromatic amines antioxidants have alkyl substituent groups of at least about 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more than about 14 carbon atoms. The general types of amine antioxidants useful in the present compositions include diphenylamines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines are also useful. Polymeric amine antioxidants can also be used. Particular examples of aromatic amine antioxidants useful in the present disclosure include: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine.

Sulfurized alkyl phenols and alkali or alkaline earth metal salts thereof also are useful antioxidants.

Preferred antioxidants include hindered phenols, arylamines. These antioxidants may be used individually by type or in combination with one another. Such additives may be used in an amount of about 0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent, more preferably zero to less than 1.5 weight percent, more preferably zero to less than 1 weight percent.

Pour Point Depressants (PPDs)

Conventional pour point depressants (also known as lube oil flow improvers) may be added to the compositions of the present disclosure if desired. These pour point depressant may be added to lubricating compositions of the present disclosure to lower the minimum temperature at which the fluid will flow or can be poured. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyarylamides, condensation products of haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479; 2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pour point depressants and/or the preparation thereof. Such additives may be used in an amount of about 0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent.

Seal Compatibility Agents

Seal compatibility agents help to swell elastomeric seals by causing a chemical reaction in the fluid or physical change in the elastomer. Suitable seal compatibility agents for lubricating oils include organic phosphates, aromatic esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example), and polybutenyl succinic anhydride. Such additives may be used in an amount of about 0.01 to 3 weight percent, preferably about 0.01 to 2 weight percent.

Antifoam Agents

Anti-foam agents may advantageously be added to lubricant compositions. These agents retard the formation of stable foams. Silicones and organic polymers are typical anti-foam agents. For example, polysiloxanes, such as silicon oil or polydimethyl siloxane, provide antifoam properties. Anti-foam agents are commercially available and may be used in conventional minor amounts along with other additives such as demulsifiers; usually the amount of these additives combined is less than 1 weight percent and often less than 0.1 weight percent.

Inhibitors and Antirust Additives

Antirust additives (or corrosion inhibitors) are additives that protect lubricated metal surfaces against chemical attack by water or other contaminants. A wide variety of these are commercially available.

One type of antirust additive is a polar compound that wets the metal surface preferentially, protecting it with a film of oil. Another type of antirust additive absorbs water by incorporating it in a water-in-oil emulsion so that only the oil touches the metal surface. Yet another type of antirust additive chemically adheres to the metal to produce a non-reactive surface. Examples of suitable additives include zinc dithiophosphates, metal phenolates, basic metal sulfonates, fatty acids and amines. Such additives may be used in an amount of about 0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent.

The types and quantities of performance additives used in combination with the instant disclosure in lubricant compositions are not limited by the examples shown herein as illustrations.

When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Typical amounts of such additives useful in the present disclosure are shown in Table 1 below.

It is noted that many of the additives are shipped from the additive manufacturer as a concentrate, containing one or more additives together, with a certain amount of base oil diluents. Accordingly, the weight amounts in the table below, as well as other amounts mentioned herein, are directed to the amount of active ingredient (that is the non-diluent portion of the ingredient). The weight percent (wt %) indicated below is based on the total weight of the lubricating oil composition.

When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Typical amounts of such additives useful in the present disclosure are shown in Table 1 below.

It is noted that many of the additives are shipped from the additive manufacturer as a concentrate, containing one or more additives together, with a certain amount of base oil diluents. Accordingly, the weight amounts in the table below, as well as other amounts mentioned herein, are directed to the amount of active ingredient (that is the non-diluent portion of the ingredient). The weight percent (wt %) indicated below is based on the total weight of the lubricating oil composition.

TABLE 1 Typical Amounts of Other Lubricating Oil Components Approximate Approximate Compound wt % (Useful) wt % (Preferred) Dispersant  0.1-20 0.1-8  Detergent  0.1-20 0.1-8  Friction Modifier 0.01-5  0.01-1.5 Antioxidant 0.1-5  0.1-1.5 Pour Point Depressant 0.0-5 0.01-1.5 (PPD) Anti-foam Agent 0.001-3  0.001-0.15 Viscosity Modifier (solid 0.1-2 0.1-1  polymer basis) Antiwear 0.2-3 0.5-1  Inhibitor and Antirust 0.01-5  0.01-1.5

The foregoing additives are all commercially available materials. These additives may be added independently but are usually precombined in packages which can be obtained from suppliers of lubricant oil additives. Additive packages with a variety of ingredients, proportions and characteristics are available and selection of the appropriate package will take the requisite use of the ultimate composition into account.

This disclosure is further illustrated by the following non-limiting examples.

Examples Test Methods

In all Examples herein, unless specified otherwise, the following properties are determined pursuant to the following ASTM standards:

Properties KV100 KV40 KV25 VI Noack Volatility Pour Point CCSV ASTM Standard D445 D445 D445 D2270 D5800 D5950 D5293

Additional bench testing was conducted for the lubricating oil compositions or formulations of this disclosure. The additional bench testing included the following: integrated mini traction machine (MTM) friction at 100 deg. C. as described below; thermo-oxidation engine oil simulation testing (TEOST 33C-SAE 932837 and SAE 962039). For some formulations, the bench testing included high temperature high shear (HTHS) viscosity at 150 deg. C. measured by ASTM D4683.

The Mini Traction Machine (MTM) is a fully automated instrument manufactured by PCS Instruments and identified as Model MTM. The test specimens and apparatus configuration are such that realistic pressure, temperature and speed can be attained without requiring very large loads, motors or structures. A small sample of fluid (50 milliliters) is placed in a test cell and the machine automatically runs either through a range of speeds, slide-to-roll ratios, temperatures and loads, or at specifically set temperature, slide-to-roll ratio and speed range to generate information regarding the friction performance of a test fluid without further operator intervention. The working of the MTM is known and familiar to those of skill in the art. In order to allow for numerical comparison of the MTM Stribeck traces, an integration method (the trapezoidal rule) was employed for each curve individually and an average integrated Stribeck friction coefficient and standard deviation for all 4 traces were calculated. The average integrated Stribeck friction coefficient provides a measure of the friction an engine will see during operation (albeit at different ratios to those calculated). The MTM integrated area value listed throughout this disclosure has been calculated using this method.

Oil life may be assessed using the Oxidative Stability Test (OST) at 165° C. In the OST, a vial is loaded with 10 mL of sample, and 50 ppm of Fe in an oil soluble form. There is a head pressure of air of 50 psi and air is bubbled in the vial at 125 ml/min. The test is run maintaining the temperature at 165° C. and, at a pre-determined interval, a small aliquot of the sample is taken out to measure the viscosity at 40° C. The measurement of the viscosity at 40° C. is similar to ASTM D445 and the results comparable. Once the viscosity increases over 200% compared to the initial viscosity, the oil is considered condemned. For the lubricating oil compositions of this disclosure, the OST (time to 200% KV40 increase) was used to quantify the oxidative stability of the inventive and comparative oil compositions.

Inventive and Comparative Lubricating Oil Compositions

A C28 Group IV base stock, dimer of 1-tetradecene, was used to formulate low viscosity engine oils and their specifications and performance test results were compared to engine oil formulations using commercially available Group IV base oils, e.g., PAO4, PAO3.6 and mPAO3.4, of similar 100 deg. C. kinematic viscosity.

FIG. 1 is a table that depicts the physical properties of the inventive base stocks (conventional C14 dimer) and comparative base stocks (metallocene PAO 3.4, conventional PAO 3.6, conventional PAO4, m-C14 dimer, Group III-Visom 4, and Group III-GTL 4) used in the evaluations. All base stocks were low viscosity having KV100 values ranging from 3.38 to 4.17 cSt. The MTM average traction coefficient of the inventive conventional C14 dimer was lower than each of the comparative base stocks measured with the exception of the metallocene C14 dimer. The metallocene C14 dimer, however, had no measurable value of CCSV at −35° C., because of its poor low temperature properties while the CCSV of the inventive conventional C14 dimer was lower than each of the other comparative base stocks.

FIG. 2 is a table that depicts the physical characteristics and performance test results of lubricating oil compositions including various low viscosity synthetic base stocks. Inventive lubricating oil compositions included the conventional C14 dimer and comparative lubricating oil compositions included metallocene PAO3.4, conventional PAO3.6 and conventional PAO4. Each of the lubricating oil compositions included 83.2 wt. % of the base stock with the remainder of the composition being a lubricating oil additive package. The performance test results for the inventive and comparative lubricating oil compositions demonstrate the significantly improved oxidative stability test results and MTM average traction coefficient test results for the inventive lubricating oil composition including the conventional C14 dimer with respect to the comparative lubricating oil compositions. The relative improvement in oxidative stability of the inventive lubricating oil composition ranged from 23.7 to 57.9%, while the relative improvement in traction coefficient of the inventive lubricating oil composition including the conventional C14 dimer ranged from 1.7 to 14.3%.

FIG. 3 is table that depicts the physical characteristics and low temperature relative viscosity reduction due to the use of inventive example 1 of SAE grade engine oil formulations using equal amount of conventional PAO4, conventional PAO3.6 and conventional C14 dimer. SAE grade engine oils evaluated were 0W-20, 0W-30, 0W-40 and 5W-30. Beneficial reduction of kinematic viscosity at 25° C. and CCSV at −35° C. was achieved in all SAE grade engine oils tested when the inventive cC14 dimer was used relative to the comparative engine oils not including the inventive cC14 dimer.

All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this disclosure and for all jurisdictions in which such incorporation is permitted.

This disclosure has been described above with reference to numerous embodiments and specific examples. Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious variations are within the full intended scope of the appended claims.

PCT and EP Clauses:

1. A lubricating oil composition comprising from 10 to 90 wt % of a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) produced by oligomerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, in the presence of a Lewis acid catalyst, and the remainder of the composition comprising one or more lubricating oil additives, wherein the lubricating oil composition provides an oxidative stability of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.

2. The composition of clause 1, wherein the base stock exhibits a mole percentage of epsilon-carbons as determined by ¹³C NMR of no less than 20 mol %, based on the total moles of the carbon atoms therein.

3. The composition of clauses 1-2, wherein the dimers are at a concentration in the range from 80 to 100 wt %, and the trimers are at a concentration in the range from 0 to 20 wt %, based on the total weight of the base stock.

4. The composition of clauses 1-3, wherein the total concentration of the dimers and the trimers combined is at least 95 wt %, based on the total weight of the base stock.

5. The composition of clauses 1-4, wherein the molecules of the dimers comprise, on average, no more than 2.0 branches attached to the carbon backbones therein.

6. The composition of clauses 1-5, wherein the base stock has a pour point as determined pursuant to ASTM D5950 of in a range from −45 to −10° C.

7. The composition of clauses 1-6, wherein the base stock has a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. of at least 500 mPa·s.

8. The composition of clauses 1-7, wherein the base stock has a kinematic viscosity at 100° C. as determined pursuant to ASTM D445 (“KV100”) in the range from 3.3 to 4.6 cSt.

9. The composition of clauses 1-8, wherein the base stock has a CCSV at −35° C. of CCSVmPa·s; when blended with a PAO reference base stock made from one or more linear alpha-olefin monomer(s) comprising 8 to 12 carbon atoms having a KV100 of 4.0 to 4.2 cSt, a pour point of no higher than −50° C., a CCSV at −35° C. of CCSV(PAO4) mPa·s, where 1200≤CCSV(PAO4)≤1500, to form a first mixture oil comprising 10 wt % of the base stock based on the total weight of the first mixture oil, a second mixture oil comprising 20 wt % of the base stock based on the second mixture oil, and a third mixture oil comprising 30 wt % of the base stock based on the total weight of the base stock, at least one of the following is met: (i) the first mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock; (ii) the second mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock; and (iii) the third mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock.

10. The composition of clause 9, wherein the base stock meets at least one of the following: (i) the first mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock; (ii) the second mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock; and (iii) the third mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock.

11. The composition of clause 9, wherein the base stock exhibits a CCSV at −35° C. lower than that of the PAO reference base stock.

12. The composition of clauses 1-11, wherein the one or more lubricating oil additives are selected from the group consisting of a detergent, dispersant, viscosity index improver, viscosity modifier, metal passivator, antioxidant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, anti-rust additive, friction modifier, extreme pressure agent and combinations thereof, and wherein the one or more lubricating oil additives comprise from 1 to 30 wt. % of the lubricating oil composition.

13. The composition of clauses 1-12 further including a cobase stock at from 1 to 30 wt. % of the lubricating oil composition, wherein the cobase stock is selected from the group consisting of a Group I base stock, a Group II base stock, a Group III base stock, a conventional Group IV base stock, a Group V base stock and combinations thereof.

14. The composition of clauses 1-13, wherein the lubricating oil composition has a kinematic viscosity at 25° C. as determined pursuant to ASTM D445 (“KV25”) at least 0.5% lower than a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).

15. The composition of clauses 1-14, wherein the lubricating oil composition has a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. at least 5% lower than a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).

16. The composition of clauses 1-15, wherein the lubricating oil composition is used as a passenger vehicle engine oil (PVEO), commercial vehicle engine oil (CVEO) or a natural gas engine oil.

17. The composition of clauses 1-16, wherein the lubricating oil composition is an SAE viscosity grade selected from the group consisting of 0W-30, 5W-30, 0W-20, 5W-20, 0W-16, 5W-16, 0W-12, 5W-12, 0W-8, and 5W-8.

18. A lubricating oil composition comprising: from 10 to 90 wt % of a base stock comprising a C28 to C32 hydrocarbon first fraction at a concentration in the range from 80 to 100 wt %, and a C42 to C48 second fraction at a concentration in the range from 0 to 20 wt %, based on the total weight of the base stock; wherein the base stock has a kinematic viscosity at 100° C. as determined pursuant to ASTM D445 (“KV100”) in the range from 3.3 to 4.6 cSt; a pour point as determined pursuant to ASTM D5950 in the range from −45 to −10° C.; and a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. of at least 500 mPa·s; and the remainder of the composition comprising one or more lubricating oil additives, wherein the lubricating oil composition provides an oxidative stability of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081. 

1. A lubricating oil composition comprising from 10 to 90 wt % of a base stock comprising a C28-C32 hydrocarbon fraction (“dimers”) and optionally a C42-C48 hydrocarbon fraction (“trimers”) produced by oligomerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, in the presence of a Lewis acid catalyst, and the remainder of the composition comprising one or more lubricating oil additives, wherein the lubricating oil composition provides an oxidative stability of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.
 2. The composition of claim 1, wherein the base stock exhibits a mole percentage of epsilon-carbons as determined by ¹³C NMR of no less than 20 mol %, based on the total moles of the carbon atoms therein.
 3. The composition of claim 1, wherein the dimers are at a concentration in the range from 80 to 100 wt %, and the trimers are at a concentration in the range from 0 to 20 wt %, based on the total weight of the base stock.
 4. The composition of claim 1, wherein the total concentration of the dimers and the trimers combined is at least 95 wt %, based on the total weight of the base stock.
 5. The composition of claim 1, wherein the molecules of the dimers comprise, on average, no more than 2.0 branches attached to the carbon backbones therein.
 6. The composition of claim 1, wherein the base stock has a pour point as determined pursuant to ASTM D5950 of in a range from −45 to −10° C.
 7. The composition of claim 1, wherein the base stock has a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. of at least 500 mPa·s.
 8. The composition of claim 1, wherein the base stock has a kinematic viscosity at 100° C. as determined pursuant to ASTM D445 (“KV100”) in the range from 3.3 to 4.6 cSt.
 9. The composition of claim 1, wherein the base stock has a CCSV at −35° C. of CCSVmPa·s; when blended with a PAO reference base stock made from one or more linear alpha-olefin monomer(s) comprising 8 to 12 carbon atoms having a KV100 of 4.0 to 4.2 cSt, a pour point of no higher than −50° C., a CCSV at −35° C. of CCSV(PAO4) mPa·s, where 1200≤CCSV(PAO4)≤1500, to form a first mixture oil comprising 10 wt % of the base stock based on the total weight of the first mixture oil, a second mixture oil comprising 20 wt % of the base stock based on the second mixture oil, and a third mixture oil comprising 30 wt % of the base stock based on the total weight of the base stock, at least one of the following is met: (i) the first mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock; (ii) the second mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock; and (iii) the third mixture oil exhibits a lower CCSV at −35° C. than the PAO reference base stock.
 10. The composition of claim 9, wherein the base stock meets at least one of the following: (i) the first mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock; (ii) the second mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock; and (iii) the third mixture oil exhibits a CCSV at −35° C. at least 50 mPa·s lower than that of the PAO reference base stock.
 11. The composition of claim 9, wherein the base stock exhibits a CCSV at −35° C. lower than that of the PAO reference base stock.
 12. The composition of claim 1, wherein the one or more lubricating oil additives are selected from the group consisting of a detergent, dispersant, viscosity index improver, viscosity modifier, metal passivator, antioxidant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, anti-rust additive, friction modifier, extreme pressure agent and combinations thereof.
 13. The composition of claim 12, wherein the one or more lubricating oil additives comprise from 1 to 30 wt. % of the lubricating oil composition.
 14. The composition of claim 1 further including a cobase stock at from 1 to 30 wt. % of the lubricating oil composition, wherein the cobase stock is selected from the group consisting of a Group I base stock, a Group II base stock, a Group III base stock, a conventional Group IV base stock, a Group V base stock and combinations thereof.
 15. The composition of claim 1, wherein the lubricating oil composition has a kinematic viscosity at 25° C. as determined pursuant to ASTM D445 (“KV25”) at least 0.5% lower than a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).
 16. The composition of claim 1, wherein the lubricating oil composition has a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. at least 5% lower than a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).
 17. The composition of claim 1, wherein the lubricating oil composition is used as a passenger vehicle engine oil (PVEO), commercial vehicle engine oil (CVEO) or a natural gas engine oil.
 18. The composition of claim 1, wherein the lubricating oil composition is an SAE viscosity grade selected from the group consisting of 0W-30, 5W-30, 0W-20, 5W-20, 0W-16, 5W-16, 0W-12, 5W-12, 0W-8, and 5W-8.
 19. A lubricating oil composition comprising: from 10 to 90 wt % of a base stock comprising a C28 to C32 hydrocarbon first fraction at a concentration in the range from 80 to 100 wt %, and a C42 to C48 second fraction at a concentration in the range from 0 to 20 wt %, based on the total weight of the base stock; wherein the base stock has a kinematic viscosity at 100° C. as determined pursuant to ASTM D445 (“KV100”) in the range from 3.3 to 4.6 cSt; a pour point as determined pursuant to ASTM D5950 in the range from −45 to −10° C.; and a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. of at least 500 mPa·s; and the remainder of the composition comprising one or more lubricating oil additives, wherein the lubricating oil composition provides an oxidative stability of greater than 100 hours (time to 200% KV@40 deg. C. increase) and a mini traction machine (MTM) average traction coefficient at 100 deg. C. of less than 0.0081.
 20. The composition of claim 19, further including a cobase stock at from 1 to 30 wt. % of the lubricating oil composition, wherein the cobase stock is selected from the group consisting of a Group I base stock, a Group II base stock, a Group III base stock, a conventional Group IV base stock, a Group V base stock and combinations thereof.
 21. The composition of claim 19 further including a Group II, III, or IV base stock as a second base stock, wherein the first base stock has a CCSV at −35° C. of CCSV(1), the second base stock has a CCSV at −35° C. of CCSV(2), and the binary mixture of the first base stock and the second base stock in the oil composition absent any component other than the first base stock and the second base stock has a CCSV at −35° C. of CCSV(3), such that: CCSV(2)>CCSV(3).
 22. The composition of claim 21, wherein: (CCSV(2)−CCSV(3))/CCSV(2)≥0.05.
 23. The composition of claim 22, wherein: the second base stock comprises a Group II or Group III base stock, and (CCSV(2)−CCSV(3))/CCSV(2)≥0.10.
 24. The composition of 23, wherein: CCSV(1)≥CCSV(2).
 25. The composition of claim 19, wherein the one or more lubricating oil additives are selected from the group consisting of a detergent, dispersant, viscosity index improver, viscosity modifier, metal passivator, antioxidant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, anti-rust additive, friction modifier, extreme pressure agent and combinations thereof.
 26. The composition of claim 25, wherein the one or more lubricating oil additives comprise from 1 to 30 wt. % of the lubricating oil composition.
 27. The composition of claim 19, wherein the lubricating oil composition has a kinematic viscosity at 25° C. as determined pursuant to ASTM D445 (“KV25”) at least 0.5% lower than a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).
 28. The composition of claim 19, wherein the lubricating oil composition has a cold-crank-simulator viscosity as determined pursuant to ASTM D5293 (“CCSV”) at −35° C. at least 5% lower than a comparable lubricating oil composition not including the C28-C32 hydrocarbon fraction (“dimers”).
 29. The composition of claim 19, wherein the lubricating oil composition is used as a passenger vehicle engine oil (PVEO), commercial vehicle engine oil (CVEO) or a natural gas engine oil.
 30. The composition of claim 19, wherein the lubricating oil composition is an SAE viscosity grade selected from the group consisting of 0W-30, 5W-30, 0W-20, 5W-20, 0W-16, 5W-16, 0W-12, 5W-12, 0W-8, and 5W-8. 